This invention relates to batteries and more particularly to a method and apparatus for increasing the useful life of a battery.
Conventional batteries for vehicles such as automobiles, golf carts, etc., are known. These generally comprise a casing containing multiple cells with anodes, cathodes, and separator plates immersed in an electrolyte. One example would be a lead acid battery having a pair of terminals, the anodes and cathodes being made of lead or a lead alloy and the electrolyte containing sulfuric acid.
Typically, such batteries have a limited useful life as cycling can result in the eventual loss of water from the electrolyte through electrolysis, releasing hydrogen gas, and/or deposition of impurities which eventually result in short circuiting within the battery.
Methods for increasing battery life have centered on programmed watering schemes, to make up for water loss. However, such schemes have no effect on the deposition of materials that can short the battery, nor are such methods available for use with sealed batteries which are commonly sold for automotive uses.
Another problem that leads to shortened battery life is corrosion of the battery components, particularly of the electrodes with corresponding penetration damage to the separation medium typically included between the electrodes in the battery. This separating medium is microporous, being in essence, a permeable membrane which may mate on the cathode side to a fiber mat material, with progressive penetration of this medium by conductive particles enhancing the likelihood that shorting will occur. The cathodes and anodes, while normally designed with a degree of corrosion resistance, will nevertheless suffer corrosion damage over the life of the battery, which can, of course, shorten battery life as well as cause release of the conductive particles that may eventually migrate to and penetrate the separator medium.
One method proposed for controlling gas emissions from a battery was proposed in U.S. Pat. No. 3,928,066 to Lewenstein, where quaternary ammonium compounds were included in a lead-acid battery with antimony grids to reduce the evolution of hydrogen gas from the anode electrode of the battery.
In French Patent No. 2,236,283 to Bonnaterre, quaternary ammonium compounds were included in nickel-iron and nickel-cadmium batteries to reduce the evolution of oxygen gas from the cathode electrode of the battery.
While securing a reduction in the evolution of gas under idealized testing conditions, the measures disclosed do not provide a long term solution to battery life.
Prevention of dissolution of a zinc anode is described in U.S. Pat. No. 3,953,242 to Hoffman, in which a primary cell has as the sole electrolyte a quaternary ammonium salt of limited solubility. A disadvantage of the limited solubility is an increase in the internal resistance of the cell.
Reduction in self-discharge is described in U.S. Pat. No. 4,064,324 to Eustace, in which an electrochemical cell contains a water soluble salt which is converted into an insoluble complex with cathodic halogen. While prolonging the shelf life of the cell, the discharge characteristics are impaired.
In U.S. Pat. No. 3,660,170 to Rampel, zinc dendritic precipitation is inhibited in alkaline zinc batteries by using a cationic high molecular weight organic polymer, preferably in the form of a hydroxide polymer, which promotes smooth and non-dendritic electro-deposition of the zinc metal onto the electrode, the polymer present at 0.1 to 10 percent by weight.
The use of the above described additives may have secured a short term performance increase, but this was found to diminish with time. To date, none of the above patented inventions have achieved commercial acceptance.
What is needed is a method and apparatus to provide a reduction in water disassociation/gas evolution, to prevent or reduce depositions which can result in cell shorting, and/or to reduce corrosion of the battery components.
It is an object of the present invention to provide a method and apparatus for increasing the useful life of a battery.
It is a further object to reduce water losses from a battery.
It is another object to reduce the detrimental effects on battery performance due to bridging precipitation of solids within a battery.
It is yet another object to provide a battery incorporating means for releasing a composition which increases the useful life of a battery.
It is a further object to provide an apparatus for progressively adding a battery life increasing composition to a battery over its useful life.
It is a further object of the present invention to reduce or eliminate corrosive damage to the battery components.
It is another object to provide a battery life extending additive for use in a battery.
It is another object to provide a composition and method for reducing self discharge and to thus substantially maintain the charge in a battery during storage.
These and other objects of the present invention are achieved by an apparatus for prolonging the useful life of a battery containing an electrolyte comprising:
a battery life extending composition; and,
means for repetitively incorporating the battery life extending composition into the battery electrolyte during the battery""s useful life.
A battery according to the invention comprises:
a housing containing an electrolyte, a plurality of anodes and cathodes disposed in the housing and connected serially and respectively to separate terminals, the battery having means for repetitively incorporating a battery life extending composition to the electrolyte so as to maintain an effective amount of the battery life extending composition in the electrolyte through the life of the battery.
A method for prolonging battery life comprises:
providing a battery containing an electrolyte therein,
providing a battery life extending composition, and,
repetitively incorporating the battery life extending composition in the electrolyte so as to maintain an effective amount of the battery life extending composition in the electrolyte for the life of the battery.
A method for reducing self discharge in a battery between cycles and/or to substantially maintain charge in the battery while in storage comprises:
providing a battery containing an electrolyte therein,
providing a battery life extending composition, and,
incorporating the battery life extending composition in the electrolyte in an effective amount for reducing self discharge and/or maintaining charge in the battery during storage.
A composition for prolonging battery life comprises an organic compound containing nitrogen and belongs to a functional group of amines. The compound more preferably is an organic amine with an n-alkyl chain and one exemplary compound is a cationic organic amine of the formula RaN+ where R is a straight, cyclic or branched hydrocarbon, and a is from 1 to 4, and optionally a carrier for encapsulating the amine, the carrier being slowly dissolvable in an electrolyte for gradual release of the amine contained therein.
Utilizing the present invention, defined quantities of a battery life extending composition are incorporated into the battery electrolyte over time so as to maintain an active concentration of the composition in the battery electrolyte. The purpose is to refresh the battery life extending composition, by repetitive addition, slow release or other means over the course of the battery""s life, as the battery life extending composition is consumed. This composition is any agent which when incorporated into a battery electrolyte reduces electrolytic reduction of water and/or reduces deposition of solids and/or inhibits corrosion of the battery components. Such a composition may comprise, though is not limited to, various amines, preferably quaternary ammonium compounds. It has been found that, in essence, replenishing such a composition by, for example, using a carrier or package that releases the composition gradually, results in a reduction of water loss and has the surprising additional advantage of preventing dendritic precipitation in a battery that can cause bridging and short circuiting that reduce battery life. Further, corrosive damage and penetrative damage of the internal battery components, most notably the separating medium, has been nearly eliminated. Failure to replenish the composition over time results in a degradation of these beneficial effects and some form of repetitive/progressive addition over time must be effected to practice the invention.